In a projection image display apparatus such as a liquid crystal projector, a display element such as a liquid crystal panel is irradiated with light emitted from a light source such as a mercury lamp, and an image formed on the display element is enlarged and projected onto a screen through a projection lens. A configuration of an optical system in the apparatus includes an integrator optical system which converges and uniformizes a light flux emitted from a light source, a color separating optical system which performs color separation, an optical modulation device which performs optical modulation in accordance with image information, a color synthesizing optical system which synthesizes the optically modulated lights, a projection optical system which enlarges and projects the synthesized light onto a projection surface of a screen or the like, an optical case which holds and fixes the various optical systems, and a housing which fixes and houses the optical case.
Here, a technique for housing each of optical components constituting the integrator optical system, the color separating optical system, and others in the optical case is disclosed (see Patent Document 1).